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  •  » A/C guru needed

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    7/26/2014 11:06 AM  #1

    Rudi
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    From: Stuck in the 50's Welland Ca
    Registered: 4/01/2013
    Posts: 3,789

    A/C guru needed

    I have a Classic Auto Air system in my 68 and the cold air output is sporadic, the compressor cycles on and off.
    The tech guy at Classic tells me it could be down a few ounces of refridgerant.

    I have automotive A/C manifold gauges and a can of 134a.
    I have read the instructions but am still unclear if it is possible to only add that small amount of 134a to the system.

    Any help on the process would be greatly appreciated.

    Good work ain't cheap, Cheap work ain't good!   Simple Man
     

    7/26/2014 12:02 PM  #2

    MS
    Forum Originator

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    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 11,746

    Re: A/C guru needed

    I do not claim to be an AC expert, but I have done my share of working on them and installing them.

    Buy one of the refill hoses at Walmart that has the gauge on it, and the gauge part screws onto the can and has a trigger.

    Hook up to the low side port and get the engine running with ac on max.  Speed up the idle to about 1500 RPM.
    Pull the trigger and let the system pull the can's contents into the port.  You will notice the included gauge is at zero while you have the trigger pulled.  Let off every few seconds and let the gauge stabilize.  When it reads right in the middl;e of the gauge, go stick your head inside the car and see if you have some improvement.  Those little refill kits have really simplified things.  They sell for about $10 as I recall.  The new ones that they advertise on TX that come with 20 ounces or freon are $35 - $40 and contain a ridiculous amount of gas.  If you ever have to add that much gas, something is wrong.

    R-134a is finicky and needs to be filled just right or things don't work right. 

    Wear eye protection.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    7/26/2014 12:17 PM  #3

    jerseyjoe
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    Registered: 4/01/2013
    Posts: 789

    Re: A/C guru needed

    Rudi, with the compressor running, look in the sight glass, if you see bubbles you are probably low on refrigerant...add some till the bubbles go away....but be sure to monitor your high and low pressures and do not exceed ......jj

       

    Last edited by jerseyjoe (7/26/2014 3:19 PM)

    "Never put a question mark where God put a period "  Richard Petty
     

    7/26/2014 1:10 PM  #4

    marsfl1
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    From: Sarasota, Fl.
    Registered: 8/27/2013
    Posts: 74

    Re: A/C guru needed

    Make sure the 3 valves on your gauges are turn off.
    Hook the can to the center hose the will be a device to puncture the can.
    Hook up the blue hose to the low side ac port it should only fit one side.
    Start you car and turn the ac on
    Open the valve on the blue hose
    Turn the can upside down 
    Slowly open the valve in the center of the gauges
    You are now adding refrigerant
    When the compressor quits cycling stop adding 

    IF IT'S TO LOUD YOUR TO OLD
     

    7/26/2014 1:52 PM  #5

    Bullet Bob
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    From: Montrose, Colorado
    Registered: 4/01/2013
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    Re: A/C guru needed

    jerseyjoe wrote:

    Rudi, with the compressor running, look in the sight glass, if you see bubbles you are probably low on refrigerant...add some till the bubbles go away....jj

    Sorry Joe, but they tell me "no sight glass on 134 systems".  If there is one on the dryer, disregard it.

    BB

    "you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
     

    7/26/2014 2:56 PM  #6

    jerseyjoe
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    Registered: 4/01/2013
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    Re: A/C guru needed

    Bullet Bob wrote:

    jerseyjoe wrote:

    Rudi, with the compressor running, look in the sight glass, if you see bubbles you are probably low on refrigerant...add some till the bubbles go away....jj

    Sorry Joe, but they tell me "no sight glass on 134 systems".  If there is one on the dryer, disregard it.

    BB

    Thats true BB, you can't base the correct refridgerant charge is when you see  a lack of bubbles, if in doubt evacuate the complete system and recharge it with the correct refrigerant WEIGHT as recommended by the manufacturer....jj

    "Never put a question mark where God put a period "  Richard Petty
     

    7/26/2014 6:13 PM  #7

    Lil' Hoss
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    From: Aberdeen, SD
    Registered: 4/04/2013
    Posts: 131

    Re: A/C guru needed

    With a recharging kit connected and the engine running at 1500 rpm, add a couple ounces and check the discharge air temp with an accurate thermometer, let it run for several minutes between adding the refrigerant,  when you have reached the point where the discharge air temp does not change anymore you have reached the correct charge. 

    The only truely accurate way to charge a 134 system is by weight, with the system completely discharged and evacuated then the proper amount by weight is added to the system, then it is full. 

    The amount of fun is directly proportionate to the damage done.
     

    7/26/2014 7:04 PM  #8

    Rudi
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    From: Stuck in the 50's Welland Ca
    Registered: 4/01/2013
    Posts: 3,789

    Re: A/C guru needed

    Thanks guys. I have the equipment just looking forn some procedural direction.
     marsfl1 thanks for that info, it seems to be what I need.

    Good work ain't cheap, Cheap work ain't good!   Simple Man
       •Thread Starter
     

    7/26/2014 10:17 PM  #9

    Bolted to Floor
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    From: Houston, Texas
    Registered: 4/01/2013
    Posts: 1,918

    Re: A/C guru needed

    I have never had the correct tools to get the specific weight of 134 into the system from a bunch of cans on any of my cars. And I'm too cheap to completely empty the system to try to get the correct amount from multiply cans. My Suburban holds over 3 pounds with the dual AC, I'll take my chances adding some.

    I use a thermometer in the vent with the idle kicked to 1500 like posted above. I place my shop fan in front of the car to keep the air moving. Also watch for condensation on the low pressure side hose fittings. They should be sweating pretty good.

    Temperatures with most of my cars (all newer models not old Mustang) gets near or just below 50 degrees.
    Good luck and Be Cool Motoring   

    John  -- 67 Mustang Coupe 390 5 speed
     

    7/27/2014 4:44 AM  #10

    hmartin025
    I FYI 24-7

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    Registered: 4/01/2013
    Posts: 365

    Re: A/C guru needed

    rudi, make sure your adding freon in the low pressure side!!!
    Howard

     

     

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